Data and Evidence

Technology is the application of scientific knowledge to solve practical problems. From simple tools to complex computers, technology shapes how humans interact with the world.

Biodiversity—the variety of life in an ecosystem—makes ecosystems more resilient. Loss of biodiversity from human activities threatens ecosystem stability worldwide.

A fair test changes one thing at a time and holds everything else steady. If you change the ramp angle and the ball at once, a difference in distance tells you nothing about which change caused it.

A bar chart compares separate categories; a line graph shows how one continuous quantity changes with another; a scatter plot looks for a relationship between two measurements. Choosing wrongly hides the pattern you measured.

One measurement can be wrong by accident. Taking three or more repeats and using the mean reduces the effect of random scatter, and comparing the repeats tells you how much to trust the mean.

Before trusting a graph, check three things: what is on each axis, what the units are, and where the scale starts. A bar chart whose axis begins at 90 rather than 0 can make a tiny difference look enormous.

Evidence is a measurement or observation anyone could repeat. An opinion is a preference. Both are legitimate, but only evidence settles a scientific question, and mixing the two is the commonest fault in a written conclusion.

Nobody counts every tree in a forest. Instead you count carefully in a small measured area and multiply up. The estimate is only as good as how typical that small area was.

Two classes can share a mean test score of 60 while one has everyone near 60 and the other has half at 30 and half at 90. The mean alone is not enough; you also need to know the spread.

Deciding what to measure is half the investigation. "Is this plant healthy?" cannot be answered directly, but height, leaf count and leaf colour can all be measured — and together they stand in for health.

A finding nobody understands has not been communicated. Lead with what you found, show the evidence that supports it, and say what you are unsure about. The order matters: conclusion first, detail second.